"If you consider NetApplications' data set, then Linux owns only about 1 percent of the desktop OS market and Windows has almost 92 percent. But if you consider all computing platforms, including mobile, than Windows has only 20 percent and Linux has 42 percent - and that would be in the form of Google's Android alone." No more or less legitimate than claiming Windows owns 92% of the market. It's all a matter of perspective.

i am not sure about that point. Besides all the usual points there is most of the time the issue of accountability.
If a company needs to run software seamlessly but problems arise during implementation there is not much of accountability i can think of. Perhaps if a company uses one of the GNU office packages who will they talk to?
And i really don't buy anymore that free argument. It does cost money to train people (down to the people actually working with programs) to have a staff to ensure operation etc... You do save the licencing cost, the rest is the same.